Pasture mixes key to cutting methane emissions

NSW Department of Primary Industries' Dr Suzanne Boschma said the research team had focused on increasing quality and lowering methane in annual fodder corps.

"Traditionally, fodder crops are an important part of our grazing system," Dr Boschma said.

"They are sown early, provide high-quality feed, and we get that nice winter production from them to carry our livestock over and fill that winter feed gap."

She said forage oats had been a traditional mainstay for late summer or early autumn-sown fodder crops, but in recent years producers had turned their attention to dual-purpose cereals and brassica crops.

There are various pasture species options to reduce methane emissions. Still, a cost-effective method in extensive grazing systems is to develop pasture mixes with high-quality feed all year round.

Species that should be considered in future pasture mixes that contain compounds such as tannins and saponins have the best potential to reduce emissions.

Pasture species that have anti-methanogenic potential due to the presence of these tannins and saponins include sainfoin, sulla, biserrula, serradella, chicory, forage rape, lotus, desmanthus and leucaena.

Dr Boschma said in addition to reducing methane emissions, other benefits of condensed tannins include improved animal growth, milk and wool production and fertility. There is a slight downside: condensed tannins can reduce voluntary feed intake or nutrient availability, but this varies with the species sown.

Methane yield is also affected by feed availability. A fodder with high digestibility, such as a legume-dominated pasture, passes through the rumen more quickly, which reduces methane yield per unit of feed intake.

Dr Boschma said the researchers' challenge was to select high-quality pasture mixes with high anti-methanogenic potential that can be readily grazed so the producer can maintain or improve animal productivity while reducing methane output.

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